Here is a summary of the NWP output for noon on Wednesday.
Issued 0504, 4/02/12

The latter half of the working week will see high pressure affecting the UK.
ECM has it over the UK with light winds for all, while GFS shows it further
north; this would allow cold ENE'lies to spread across much of England and
Wales with a snow risk in southern and some eastern areas. Interestingly
both runs agree on an upper ridge building to the west by day 10, even
though they get there via different means. This means there's a chance of a
northerly spell in the longer term, but of course it's still very much
subject to change!

Analysis and evolution to T+120 via GFS
SSW'lies cover the UK ahead of a trough to the west. The trough crosses the
UK overnight, with southerlies in advance and westerlies following behind. A
second trough moves eastwards on Monday, leading to a small low off Kent on
Tuesday. The majority of the UK lies under a ridge by this stage.

T+120 synopsis
http://www.wetterzentrale.de/wz/pics/Rtavn12014.png
http://www.wetterzentrale.de/wz/pics/Rtavn1201.png
http://www.wetterzentrale.de/wz/pics/Rukm1201.gif
http://www.wetterzentrale.de/wz/pics/Recm1201.gif
http://www.wetterzentrale.de/wz/pics/Rjma1201.gif
The jetstream chart shows a ridge over the northern half of the UK with a
weak easterly flow over northern England. There's a weak trough over the
southern half of the UK. At the 500hPa level GFS brings NE'lies with an
upper ridge to the north. MetO has SW'lies aloft with a trough to the west,
while ECM has a ridge over Scotland and Northern Ireland with upper NE'lies
over England and Wales. GEM shows trough disruption to the west with upper
ENE'lies for the UK, while JMA is far more progressive with SSW'lies aloft.
At the surface GFS has NE'lies for most due to a ridge east of Scotland.
MetO has a trough moving eastwards with southerlies in advance and
westerlies following behind. A ridge from the east covers northern England
with ECM, leading to southerlies to the north and NE'lies to the south. GEM
has easterlies and SE'lies as a low lies to the SW, while JMA is closer to
MetO with a trough crossing the UK.

Evolution to day 7
ECM brings a high over the UK on days 6 and 7.
GFS has high a ridge over Scotland on days 6 and 7, with cold or very cold
ENE'lies over England and Wales.

Looking further afield
The high declines SW'wards on day 8 with ECM, leading to westerlies. There
are further westerlies on days 9 and 10.
GFS shows high pressure to the WNW on day 8, with ENE'lies for England,
Northern Ireland and Wales and NW'lies for much of Scotland. The high drifts
westwards on day 9, allowing NNW'lies to move across most of the UK. Day 10
sees colder NNW'lies as the high continues to drift westwards.

Ensemble analysis
http://www.meteociel.com/cartes_obs/...&ville=Londres
The GEFS shows a generally cold outlook for at least the next week to 10
days, with the mean maximum only a couple of degrees above freezing.

ECM ensembles
http://www.meteogroup.co.uk/meteo/ep...tt6-london.gif
ECM shows a slightly milder outlook compared to GFS, with a couple of
less-cold days on the 4th/5th followed by two colder days and then a gradual
rise in temperatures.